1. Field of the Invention
This invention relates to a composite film suitable for use per se or in garments that provide protection against contact with hazardous substances. More particularly, the invention concerns such a film which includes at least two different film layers, one film layer being of polyvinyl or polyvinylidene fluoride and the second film layer being of polyvinyl alcohol.
2. Description of the Prior Art
Workers in many industries and professions need protection from hazardous substances. Some such protection is often in the form of a disposable, or limited use, gloves or outer garments which prevent worker's skin or clothing from contacting the hazardous material. Surgeons, chemical-plant workers, asbestos removers, radioactive-contamination cleaners, disposers of chemical wastes and farmers handling various agricultural chemicals and pesticides are among the many users of such protective gloves and garments. Such gloves and garments need to be as impervious to chemicals as is consistent with safety, comfort and cost. Many of the disposable garments now available commercially provide only short-term protection. Chemicals can pass through the garments in but a few minutes, after which the wearer must immediately leave the work area, remove the contaminated clothing, and bathe. Such short-term protection results in lost production time and, more importantly, in exposure of the worker to the hazardous substances.
Goldstein, U.S. Pat. No. 4,272,851, discloses protective garments made of spunbonded, polyethylene nonwoven sheet (e.g., "Tyvek", sold by E. I. du Pont de Nemours and Company) which may be coated or laminated on one side with a polyethylene film. Du Pont brochure, E-32814, entitled "For Hazardous or Dirty Jobs. . .Protect Your Workers with Garments of "TYVEK" Spunbonded Olefin" discloses garments made from the spunbonded olefin nonwoven sheets laminated with coextruded, multilayered thermoplastic film (e.g., "Saranex", sold by Dow Chemical Company) along with the permeation characteristics of these laminated sheets. "Saranex" is a three-layered laminate of "Saran" vinyl chloride/vinylidene chloride copolymer film, sandwiched between two layers of polyethylene.
Though not related to fabrics for protective garments, Dehennau, U.S. Pat. No. 4,585,694, and Decroly and Dehennau, U.S. Pat. No. 4,659,625, disclose films of polyvinyl fluoride or polyvinylidene fluoride bonded to another polymer. Kuga et al, U.S. Pat. No. 4,230,654, discloses polyvinyl alcohol films coated with copolymer compositions. Bolt, U.S. Pat. No. 4,416,946, discloses a film of polyvinyl alcohol laminated to a substrate, such as a fluorocarbon material, which is then treated with iodine to form a polarizing sheet.
The known protective garments have enjoyed some commercial success. However, if longer times were required before hazardous substances could permeate or pass through the garment (i.e., if the garments possesssed longer "hold-out times") the garments would have considerably greater utility. Accordingly, an object of this invention is to provide a composite film that has improved hold-out time characteristics.